Production of granular detergent



Patented July 18, 1950 PRODUCTION OF GRANULAR DETERGENT MIXTURES James Douglas MacMahon, Niagara Falls, and Lorenzo D. Taylor, Lewis'ton, N. Y., assignors to Mathieson Chemical Corporation, a corporation of Virginia NoDrawing. Application July 3, 1946,

Serial No. 681,410

4 Claims.

Our invention relates to a method of producing granular, non-caking, free-flowing alkaline compositions adapted for use in cleansing, disinfecting and other operations in which alkaline detergents are employed in aqueous solution.

It is, of course, old to prepare mixtures of detergent materials in granular form in order to simplify their handling, storage and transport. However, in many of such mixtures, the particles or granules vary greatly in size which is highly disadvantageous, among other reasons, because of the resultant varying rates of solubility. Mixtures currently available, in which the particles are sufiiciently uniform in size are, in general, produced by processes requiring the re-working or further working of particles which are either too large or too small as determined by selected limits. Thus, it is the common practice to subject the large particles, after separation by screening, to a grinding operation to reduce them to a size within the permissible limits and to return the fine particles to the agglomerating device.

. An advantage of the present invention resides in the fact that it greatly reduces the quantity of material which must be subjected to this additional or further processing. Our invention is ,specifically directed toward providing granular mixtures of detergent materials characterized in the respect of particle size in that not more than about 20% of the mixture when screened with screens of the Tyler series is retained on the 20 mesh screen and in that not substantially more than passes through the 65 mesh screen.

According to the conventional method of preparing granular mixtures of the type here involved, the comminuted material representing the charge stock, after being wetted with water or while being wetted with water or steam is agitated in a mixing device such as a horizontal rotating drum for a period of time sufiicient to achieve agglomeration. Subsequent processing involves screening of the agglomerated mass to the desired particle sizing with return of the undersized material to the mixing device and crushing of .the oversized agglomerates.

We have now discovered that the amount of water employed in the agglomeration of mixtures of powdered or comminuted detergent materials is a critical factor. More particularly, we have found that if the quantity of water used in the agglomeration, as carried out with addition of the water during the agitation period, is restricted within the limits 70-95% of that just suiiicient to convert the free-flowing mass to a paste. a minimum of 70% of the agglomerated product will have a particle size within the range 20-65 mesh (Tyler series). In most instances, but not always, the maximum conversion to the desired particle size is achieved by using -93% of the amount of water needed to form a paste. optimum proportion of water with respect to that just sufiicient to convert the mass to a pasty consistency depends largely upon the composition of the mixture and to a minor extent upon the type of mixing employed. It may be advantageous to add the water at an elevated temperature particularly where materials that are difiicult to hydrate are present in the mixture. After the agglomeration, which in any event proceeds with the evolution of heat, the mass should be cooled to a temperature of 30 C. or less in order to prevent a subsequent tendency to cake. Surface active agents where used may advantageously be dissolved in the water. In such cases the dry material subjected to the simultaneous agitation and wetting may consist of only one compound.

Our invention is particularly applicable to the production of granular mixtures comprising soda ash or mixtures of soda ash and sodium bicarbonate and phosphates such as tetrasodium pyrophosphate, sodium tripolyphosphate, trisodium phosphate, etc.. but is not limited to such mixtures. Thus, it may be applied, for example, in the production of a granular product consisting of borax and a suitable wetting agent. In all cases, the material wetted should be of such particle size that a major portion will pass through a 65 mesh Tyler screen.

Our invention may be practiced using a conventional pug mill or any type of mixing device applying a mild mechanical action. Mixers of the horizontal type are preferred. In general, it is best not to add the water until the dry materials have become intimately mixed. The water should beadded slowly in all cases. Spray devices may be used, with advantage, particularly in large scale operations. After the last of the water has been added, the mixing should be continued for several minutes before the granulated product is cooled.

In the following examples, submitted in further illustration of our invention, all parts are by weight andall materials are anhydrous unless otherwise specified:

firrcmple 1 parts of water was slowly added to an agitated mixture consisting of parts of sodium carbonate, 60 parts of sodium silicate, and 60 The 18.1% was retained on a 20 mesh screen, 57.8% on a 48 mesh screen, and 18.3% on a 65 mesh screen,

while 5.8% passed throughthe 65 mesh screen.

Example 2 140 parts of water was slowly added to an agi tated mixture consisting of 240 parts of sodium carbonate and 60 parts of tetrasodium pyrophos phate. The 140 parts of water was equivalent to 93.5% of that just required to form a paste from the dry materials. Following a few minutes ad-- ditional agitation, the wetted material was aircooled and screened; 19.7% was retained on the 20 mesh screen, 59.0% on the 48 mesh and 11.9% on the 65 mesh ,with 9.4% passing through the 65 mesh. The screened material was found to be of substantially uniform chemical composition. That passing through the 20 mesh screen and retained on the 48 and 65 mesh screens analyzed 64.6% sodium carbonate. v Example 3 To 150 parts each of sodium carbonate and sodium silicate was slowly added 94.5 parts of wa ter, 70% of that just required to convert the dry materials to a paste. When the resulting material was subjected to screening, 9.4% remained on the 20 mesh screen, 73.5% on the 48 mesh, and on the 65 mesh. Only the 65 mesh screen.

Example 4 60 parts of water, 80%of that necessary to form a paste, was slowly added to a dry mixture consisting of 225 parts of sodium carbonate, 56.3

Example 5 1.8% passed through To 225 parts of sodium carbonate, 56.3 parts To 80 parts of borax was slowly added, with agitation, 5 parts of along chain alkyl dlmethyl benzyl ammonium chloride dissolved in 15 parts of water, about 80-85% of that required to form a paste. In excess of 70% of the granular product was of a particle size within the range 20-65 mesh.

Example 7 2.5 parts of diisobutyl phenoxy-ethyl dimethyl benzyl ammonium chloride in 14.5 parts of water was slowly added, with agitation, to a dry mixture consisting of parts'of sodium carbonate, 18 parts of tetrasodium pyrophosphate and 20 parts of trisodium phosphate dodecahydrate. In excess of 70% of the resulting product was of a particle size within the range 20-65 mesh. The

6 amount or water added to the dry materials was equivalent to about -90% of that required to form a paste.

Example 8- A similar product was obtained by the slow addition of 10.40 parts of water, approximately of that required to form a paste, to a dry agitated mixture consisting of 8.70 parts of trisodium phosphate dodecahydrate, 17.80 parts of sodium carbonate, 28.30 parts of sodium bicarbonate, 4.35 partsof sodium silicate pentahydrate, 8.70 parts of tetrasodium pyrophosphate and 21.75 parts of a high molecular weight fatty alcohol sulfate.

Example 9 t The addition or 100 parts or water to a dry mixture of 200 parts of sodium carbonate and 100 parts of sodium tripolyphosphate, NasPaOm. gave a paste. However, when 80 parts by weight of water instead of 100 was used a granular product was produced, 21% of which was retained on a '20 mesh screen, 54% on 48 mesh and 13.2% on 65 mesh.

Example 10 24.4 parts of water was added slowly, with agitation to a mixture consisting of 50 parts or sodium carbonate, 14 parts'ot tetrasodium pyrophosphate, 7 parts of a higher fatty alcohol sulphate and 7 parts of sodium-p-toluene-sulphochloramide. In excess of 70% of the resulting product which analyzed 2.10% available chlorine was 01' a particle size within the range 20-65 mesh. The amount of water added to the dry materials was equivalent to about 8090% of that required to form a paste.

Example 11 decreases until finally there is no agglomeration whatsoever.

, We claim:

1. A process for granulating dry powdered detergent mixtures of such particle size that a major portion passes through 65-mesh (Tyler) and which consist of soda ash and at least one material selected from the class consisting of sodium silicate, sodium bicarbonate and sodium phosphates which comprises mechanically agitating the dry powdered mass in the presence of water which is slowly added in an amount exceeding about 10 per cent by weight of the mass but between about 70 to per cent of the water required to convert the dr powdered mass to a paste wherein there is just suilicient water to form the continuous phase and convert the freeflowing mass to a unitary mass, and screening the granulated mass to recover the fraction within the size range of 20 to 65 mesh (Tyler).

.2. The process of.claim 1 wherein the dry powdered mixture contains a major proportion of soda ash.

3. The process of claim 1 wherein a surface active agent is dissolved in the water employed. 

1. A PROCESS FOR GRANULATING DRY POWDERED DETERGENT MIXTURES OF SUCH PARTICLE SIZE THAT A MAJOR PORTION PASSES THROUGH 65-MESH (TYLER) AND WHICH CONSIST OF SODA ASH AND AT LEAST ONE MATERIAL SELECTED FROM THE CLASS CONSISTING OF SODIUM SILICATE, SODIUM BICARBONATE AND SODIUM PHOSPHATES WHICH COMPRISES MECHANICALLY AGITATING THE DRY POWDERED MASS IN THE PRESENCE OF WATER WHICH IS SLOWLY ADDED IN AN AMOUNT EXCEEDING ABOUT 10 PER CENT BY WEIGHT OF THE MASS BUT BETWEEN ABOUT 70 TO 95 PER CENT OF THE WATER REQUIRED TO CONVERT THE DRY POWDERED MASS TO A PASTE WHEREIN THERE IS JUST SUFFICIENT WATER TO FORM THE CONTINUOUS PHASE AND CONVERT THE FREEFLOWING MASS TO A UNITARY MASS, AND SCREENING THE GRANULATED MASS TO RECOVER THE FRACTION WITHIN THE SIZE RANGE OF 20 TO 65 MESH (TYLER). 